Due to their rich selection of materials and wide variety of functions, attempts to apply polymer materials for optical purposes have been growing in recent years. For example, polymer molded products in which fine scale one or two-dimensional structures are formed can be used as light control elements or light diffraction elements.
A known molded product of this type is a polymer film having a phase structure whereby in a polymer matrix, multiple structures having an index of refraction different from that of the matrix are oriented in the same direction (see Documents 1 and 2). Polymer films having this type of phase structure impart a diffraction spot when incident light is parallel to the axial direction of the structure, due to the above-described layout of the structure. Therefore polymer films of this type can be used as light diffraction elements for diffracting incident light at a specific position and a specified intensity.
A film having such a structure and a method of fabricating same is set forth in Document 1. In Document 1, the film is produced by photopolymerizing at a fixed film thickness by irradiating with light from a linear light source directed from a specified angle. Film fabricated in this way selectively diffracts light incident at a specific incidence angle.
Document 2 sets forth a film with a sea-island phase structure; this film is formed such that a columnar island structure extends in the film thickness direction within a sea structure.
In this method, the photo polymerizable composition is first coated onto a substrate at a uniform thickness, then that surface is covered with a mask. A large number of holes are randomly patterned into this mask. Next, ultraviolet light is shone on the surface of the photo polymerizable composition through this mask, thus forming columnar bodies which serve as the island structures. After the columnar bodies are formed, the mask is removed and further ultraviolet radiation is shone on the film, thereby polymerizing the sea structure portions.
Document 1: JP-A-03-284702
Document 2: JP-A-11-287906